Conventionally, there is known a technique to detect breakage of a tool after machining a workpiece in a machining apparatus (for example, patent documents 1 to 3). In the patent document 1, a technique is disclosed, in which technique each of a plurality of detecting devices is disposed on a side position of a corresponding tool of a plurality of tools attached to a multi-spindle head to detect breakage of the tools. In the patent document 2, a technique is disclosed for a tool delivery device for storing a tool attached to a spindle in a tool magazine, in which technique there is provided a linear movement zone on the way of a movement way of the tool, and a tool breakage detecting device is provided in the linear movement zone. In the patent document 3, a detector and a tool approach section for detecting breakage of a tool stored in a tool stocker are disclosed.